What is the Nature of Inertia?
Goal: To determine the relationship between inertia and
Newton’s 1st Law of Motion
Materials: Eggs, cloth napkin, bowl, index card, coin, beaker, roller skate, small mass, tape.
Procedure: Station 1: Magic Eggs
First, spin the egg labeled “A”. Then, place your finger on it gently to make it stop spinning.
Repeat with the egg labeled “B” and record your observations.
Did both eggs spin evenly? Explain.
Did the eggs react differently when you tried to stop them? Explain
Which egg is hard-boiled (solid all the way through) and which one is raw (liquid inside)? Explain.
Station 2: Clear the Table!
Place the bowl on the cloth napkin on the desk.
With a quick jerk, pull the napkin out from under the bowl.
What happened to the bowl? Explain in terms of Newton’s 1st law.
Station 3: Coin in a Cup
Put the index card on top of the small beaker.
Place the coin in the center of the card.
Using your index finger, quickly flick the edge of the card.
What happened to the coin? Why didn’t it move with the card? How does this demonstrate Newton’s 1st law?
Station 4: Buckle Up for Safety!
Stand the textbook on its end near the end of the table.
Place the small mass on the front of the roller skate.
Point the skate at the book and give it a gentle push.
Describe what happened to the skate and the mass when they hit the textbook. How does this demonstrate Newton’s 1st law?
Using the same setup, this time tape the mass securely to the skate.
Push the skate toward the book.
Describe what happened to the skate and the mass when they hit the textbook. How does this demonstrate Newton’s 1st law? What are the unbalanced forces?
Station 5:Both moving and nonmoving objects have inertia.
Explain why throwing a bowling ball and catching a thrown bowling ball are hard.
Station 6:Why is it harder to run with a backpack full of books
than to run with an empty backpack?
KEY
Procedure: Station 1: Magic Eggs
First, spin the egg labeled “A”. Then, place your finger on it gently to make it stop spinning.
Repeat with the egg labeled “B” and record your observations.
Did both eggs spin evenly? Explain.
The liquid inside the raw egg sloshes, so the raw egg doesn’t spin smoothly,
as the hard-boiled egg does.
Did the eggs react differently when you tried to stop them? Explain
The hard-boiled egg stops as a whole. But the raw does not stop as a whole
because the liquid inside keeps spinning after the shell has been stopped.
Which egg is hard-boiled (solid all the way through) and which one is raw (liquid inside)? Explain.
“A” is hard boiled; “B” is raw based on the results as described above.
Station 2: Clear the Table!
Place the bowl on the cloth napkin on the desk.
With a quick jerk, pull the napkin out from under the bowl.
What happened to the bowl? Explain in terms of Newton’s 1st law.
Station 3: Coin in a Cup
Put the index card on top of the small beaker.
Place the coin in the center of the card.
Using your index finger, quickly flick the edge of the card.
What happened to the coin? Why didn’t it move with the card? How does this demonstrate Newton’s 1st law?
The coin remains at rest. When the card is removed quickly, there is not
enough friction to move the coin. So, the coin falls into the cup.
Station 4: Buckle Up for Safety!
Stand the textbook on its end near the end of the table.
Place the small mass on the front of the roller skate.
Point the skate at the book and give it a gentle push.
Describe what happened to the skate and the mass when they hit the textbook. How does this demonstrate Newton’s 1st law?
Objects in motion remain in motion, even when the skate stops moving.
Using the same setup, this time tape the mass securely to the skate.
Push the skate toward the book.
Describe what happened to the skate and the mass when they hit the textbook. How does this demonstrate Newton’s 1st law?
Both stopped. The tape acts like a seatbelt.
Station 5:Both moving and nonmoving objects have inertia.
Explain why throwing a bowling ball and catching a thrown bowling ball are hard.
Catching a bowling ball is as hard as throwing it because the bowling ball has
the same inertia in both cases. Lots of mass means lots of inertia. The bowling ball does not want to stop and it is hard to get it moving.
Station 6:Why is it harder to run with a backpack full of books
than to run with an empty backpack?
Starting and stopping will be
harder because the extra mass increases your inertia. In addition, the books
in the backpack act as the liquid inside a raw egg does. As you bounce up,
they resist your upward movement. As you bounce down, they are still moving
upward.